A couple of days ago our Transit Custom audio unit got stuck with the Audio Off message, no volume control response, no steering wheel audio controls work and tapping the 'audio' icon on the Sync 3 screen had no effect.

We browsed this forum a bit and found a couple of references to reseating a fuse. I couldn't find the fuse mentioned in the post and knew battery access was easy, so pulled the battery terminal wondering whether such an easy fix would reset whatever state it had got stuck. In all honesty, I didn't expect it to work, but I didn't expect it to do any harm.

However, harm has occurred. Since this moment we've had very weird lighting issues. Specifically:

• No interior lights come on when doors are open, either in the passenger compartment or load compartment.
• Headlamps and side lights work only on the front left, the front right does not light up.
• Tail lights work only on the right, not on the left.
• Indicators work opposite to the lights, only working front right and rear left. Indicators on the front left and rear right don't work with the indicator stalk or hazard light switch.

The "audio off" problem still exists, apart from the lights and audio I *think* everything else is working.

Looking at other posts and this technical bulletin (https://www.scribd.com/document/700207347/2020-Transit-2019) it looks likely that something is going on with the BCM, but I can't explain why that would happen with a battery disconnect/reconnect.

I looked for a wiring diagram to see if I could find the common threads for the things that have stopped working but I can't find a wiring diagram for the post 2019 model.

I don't have Forscan. I do have a Bluetooth ELM327 and Torque, there are no ECU fault codes but I wouldn't expect this toolsuite to pick up Ford-specific fault codes.

Is there anything that comes to mind as a root cause or next step, short of an emergency trip to a Ford dealer?

Adding new context: It has occurred to me that we removed several fuse covers while looking for the aforementioned audio fuse. I think it *very* unlikely, but it is possible that we nudged something. The fuse box diagrams are pretty vague when it comes to which fuse does what in regard to the BCM, does anyone have a better wiring diagram or fuse diagram that supports the possibility that one of the fuses has a loose connection and is accountable for the faults listed above?

In particular, our fuse box has fuse 86 (https://www.fordservicecontent.com/Ford_Content/vdirsnet/OwnerManual/Home/Content?variantid=8255&languageCode=en&countryCode=USA&moidRef=G539642&Uid=G2227171&ProcUid=G2227172&userMarket=USA&div=f&vFilteringEnabled=False&buildtype=web) completely missing.

34 minutes ago, StuartL_UK said:

Adding new context: It has occurred to me that we removed several fuse covers while looking for the aforementioned audio fuse. I think it *very* unlikely, but it is possible that we nudged something. The fuse box diagrams are pretty vague when it comes to which fuse does what in regard to the BCM, does anyone have a better wiring diagram or fuse diagram that supports the possibility that one of the fuses has a loose connection and is accountable for the faults listed above?

In particular, our fuse box has fuse 86 (https://www.fordservicecontent.com/Ford_Content/vdirsnet/OwnerManual/Home/Content?variantid=8255&languageCode=en&countryCode=USA&moidRef=G539642&Uid=G2227171&ProcUid=G2227172&userMarket=USA&div=f&vFilteringEnabled=False&buildtype=web) completely missing.

There's this thread on this group if not seen already fingers crossed it's of use for you 🤞

2019 Custom fuse boxes - Ford Transit Club - Ford Owners Club - Ford Forums https://share.google/pvKqWktMGflFdO1g6

2 minutes ago, doggsbody said:

There's this thread on this group if not seen already fingers crossed it's of use for you 🤞

2019 Custom fuse boxes - Ford Transit Club - Ford Owners Club - Ford Forums https://share.google/pvKqWktMGflFdO1g6

Thanks. My driver's compartment fuse box is identical to this one: 

Where you see a fuse in the bottom left (partially obscured by the metalwork) I have an empty slot. The online manual (the manual in the van is for the wrong fuse box) labels this fuse (86) as BCM. I have now tried putting a fuse in here and it hasn't changed symptoms.

The Ford documents do seem to show a passenger side fuse box with relays in it, and I don't have that. I assume that everything is controlled by the BCM...?

The additional problems sound to me like they have been caused by disconnecting and reconnecting the battery too quickly.

To reset all modules you need to disconnect the battery negative lead for at least twenty minutes. Then reconnect the battery and WAIT, do nothing for 5 minutes. Then turn on the ignition. This will reset all the vehicles modules and allow them to boot up in the correct sequence.

Good luck, I hope this will clear all your new faults, and it may reset the Sync 3.

11 hours ago, unofix said:

The additional problems sound to me like they have been caused by disconnecting and reconnecting the battery too quickly.

To reset all modules you need to disconnect the battery negative lead for at least twenty minutes. Then reconnect the battery and WAIT, do nothing for 5 minutes. Then turn on the ignition. This will reset all the vehicles modules and allow them to boot up in the correct sequence.

Good luck, I hope this will clear all your new faults, and it may reset the Sync 3.

Thanks for the suggestion. I disconnected for 30m, connected, waited 10m, then checked the lights and still no interior light trigger and the hazard lights only light up opposite corners.

7 hours ago, StuartL_UK said:

I disconnected for 30m, connected, waited 10m, then checked the lights and still no interior light trigger and the hazard lights only light up opposite corners.

Then I'm afraid it's very much like water ingress to the Body Control Module (BCM) which is a common problem with many Ford models.

You are going to need to use FORScan and see what DTC's it can read.

On 4/7/2024 at 8:59 PM, unofix said:

FORScan (for use with Windows Laptop) : https://forscan.org/download.html

It's what many Ford owners use including some Ford technicians.

• vLinker FS, cable for laptop: https://www.amazon.co.uk/Vgate-vLinker-Adapter-FORScan-MS-CAN/dp/B0952P4MLP

OR

• OBDLINK EX, cable for laptop: https://www.amazon.co.uk/OBDLINK-EX-FORScan-OBD-Adapter/dp/B081VQVD3F/ref=sr_1_5

For diagnostic use only:

• vLinker FD, for android phone: https://www.amazon.co.uk/Vgate-Bluetooth-vLinker-Scanner-Diagnostic/dp/B08H82WC8L
• vLinker FD+, for iPhone: https://www.amazon.co.uk/Vgate-Bluetooth-vLinker-Scanner-Diagnostic/dp/B08H8JHWP2